20 Replies Latest reply on Jul 23, 2009 8:22 AM by vidkidfx

    "Stuttering" when panning/zooming a still image...?

    theboyk Level 1
      Hello.

      I'm working on a small project which is basically a series of zooms/pans on still images. The pans/zooms are quite slow and take place over about 6-8 seconds. There's nothing too fancy going on here, but I notice that when I do a RAM preview or render out a comp, I get small "stutters" in some of them. Does anyone have any ideas why this would be happening and any suggestions on making these animations a little more "smooth". I mean, these things aren't complex at all, and overall they're quite smooth, but there's still times when I get these stutters and I can't figure out why they'd be happening? Would appreciate some advice!
      Thanks,
      Kristin.
        • 1. Re: "Stuttering" when panning/zooming a still image...?
          Jonas Hummelstrand Level 2
          Your problem can be broken down into two solutions. Start by seeing if the jerkiness is happening at the same point in time every time you play the clip, both as a RAM preview and as a rendered movie. If the stutter happens at different points in time it's because your computer can't play back the frames fast enough. In that case, turn off the "Preview to External Monitor" and/or lower the size and resolution of your comp viewer, and render to a codec that your computer can play, perhaps QuickTime PhotoJPEG at 75% or less.

          If the stutter occurs at the same time no matter how you view the clip, you need to realize how our brain works. Animation is all about tricking the brain to think that a bunch of still images are really a moving image. If things in your movie move too much between frames, you break this illusion and the brain sees stutter or jerkiness.

          How to solve this problem:
          1. Animate at a higher frame rate (doesn't really matter unless you can also playback the finished movie at a higher frame rate.)

          2. If you are outputting for broadcast or DVD (and you know what you're doing) render the finished movie with fields which will let you see twice the frame rate on a TV set.

          3. Move the objects slower so that the difference between consecutive frames is lowered.

          4. Turn on Motion Blur for all the moving objects (only helps for objects you've animated inside AE.)

          5. Raise the "Shutter Angle" in "Composition Settings" -> "Advanced" to get more motion blur.

          - Jonas Hummelstrand
          http://generalspecialist.com/
          • 2. Re: "Stuttering" when panning/zooming a still image...?
            theboyk Level 1
            Hmmm, well, I don't think it's a computer issue in terms of being able to handle the video. I'm running this on a Mac Pro (quad-core Xeon) with 8GB RAM with nothing running be AE. The more detailed I looked at it, I realized it wasn't actually happening in RAM preview, but rather in my renders. Actually, I think it's a Quicktime issue possibly because the same renders, when played on a different computer (and old G4 Powerbook), there's no stutter at all (and these test renders are at half the size of the original with H.264 compression at "medium" settings, as well as full resolution outputs (no compression) then burned to DVD (via DVD Studio Pro). Again, the issue only seems to happen on the Mac Pro when viewing via Quicktime or Apple's DVD Player software (Quicktime). So....I think it's actually a Quicktime issue?

            But, while I have you would you be able to expand on your second point about lettings one see twice the frame rate on a TV set?

            Thanks,
            Kristin.
            • 3. Re: "Stuttering" when panning/zooming a still image...?
              Mylenium Most Valuable Participant
              Well, actually you don't really see "twice the framerate" with interlaced footage. Back in the past interlaced stuff was used because the equipment wasn't fast (way back, when vacuum electron tubes were used to modulate frequencies), but as a side effect, it worked in favor how the human eye perceives the world: it is focused on detecting motion and variations in brightness before actually evaluating color. Simply put - interlaced footage looks "smoother", because the alleged perceived changes in motion are cut in half by distributing them onto the different fields (or alternating scanlines). Instead of "jumping" from frame to frame, there is now an additional phase inbetween that disguises the changes in the pixel position. These positive effects are however only noticable if the difference exceeds a certain threshold. Also note, that often field rendering is still not necessary if things like motion blur or certain effects like heavy blurs and glows are used. The key point really is to visually blend things, so it is perceived as pleasing by the human eye. Which technical methods to employ to achieve that is still your decision. Now all theory is grey, so I recommend you simply play with the render settings and run a few comparative tests when you have time, exploring the pros and cons. After while, you will simply develop a natural gut feeling for these things... ;-)

              Mylenium
              • 4. Re: "Stuttering" when panning/zooming a still image...?
                Jonas Hummelstrand Level 2
                It is certainly possible to render video files that no computer in the world is capable of playing in realtime.

                While playing in QuickTime Player, hit Cmd-I and see what it says under "Playing FPS." If it is less than you rendered, your machine can't read/decode the video fast enough to play in realtime.

                - Jonas Hummelstrand
                http://generalspecialist.com/
                • 5. Re: "Stuttering" when panning/zooming a still image...?
                  theboyk Level 1
                  Yea, I don't think it's the computer not being able to play the file. It's a 640 x 260, 29.97 FPS H.264 movie file playing back on a quad-core Intel Mac Pro with 8GB RAM. I would have to imaging the machine should have no issue playing it?

                  I just downgraded to Quicktime 7.4 in the hopes that would solve the problem, but nothing. I'm pulling my hair our here. This seems like such a simple operation, I have no idea why I keep getting this stuttering problem...?

                  k.
                  • 6. Re: "Stuttering" when panning/zooming a still image...?
                    Andrew Yoole MVP & Adobe Community Professional
                    It depends what you mean by "stutter". If your renders are progressive (non interlaced - which I assume they are considering your resolution, and which all RAM previews are anyway) then movements at certain speeds can result in a strobing/flickering kind of stutter. Horizontal movement is particularly prone to this problem. It's not a software issue - it has to do with the nature of video images and the speed with which the human eye views each frame.

                    Experiment with slightly slower movement and see if the problem lessens or disappears.
                    • 7. Re: "Stuttering" when panning/zooming a still image...?
                      theboyk Level 1
                      OK, let me explain what I mean by "stutter". I have a series of still images which I am doing short, slow, pan & zooms of. The pan and zoom is slow. About 8-10 seconds for a very small pan/zoom (nothing fast here). As it's doing this pan/zoom, it starts off smooth, then it gets jumpy/stutters like it's skipping frames/pausing VERY quickly.

                      It's not "flickering" in respect to what you'd expect from interlace issues with thin, horizontal lines in the image (I've also compensated for this by adding a slight blur to my images which reduced the "flickering"). The problem is more an issue with the "smoothness" of the pan/zoom. Again, this movement is quite slow/minimal, but it just seems to "stall" very quickly (which results in what looks like a "stutter", or someone very very quickly hitting the pause/play button repeatedly).

                      Now, this isn't happening (or at least not from what I can tell) in RAM previews, but rather on resulting renders (both "lower res" 640 x 360, 29.97 FPS H.264 movies and full res 1280 x 720 burned DVDs played on my Mac Pro). So, maybe there's something going on in the rendering that is causing this? When rendering, where do I deal with progressive/non-interlaced settings? Maybe there's something wrong there?

                      Thanks!
                      Kristin.
                      • 8. Re: "Stuttering" when panning/zooming a still image...?
                        theboyk Level 1
                        Ok, did more testing.

                        RAM previews are fine, no stutter.

                        Rendering out (quicktime, no compression, full size, full quality, 29.97 FPS) and burning to a SD DVD via DVD Studio Pro, playing on a SD DVD player to a SD 16:9 television, as well as SD 4:3 television (via same DVD player), plays very, very smooth.

                        Render out the same video (quicktime, "high" quality H.264 compression, half-size, 29.97 FPS) and playback on various systems (using various versions of Quicktime on various Macs, intel and non-intel) and I get the stutter?

                        I also tried playing the DVD back via the internal DVD player on the Mac and I get the stutter?

                        Any clue why there's the stutter when playing back on the computer?

                        Regards,
                        Kristin.
                        • 9. Re: "Stuttering" when panning/zooming a still image...?
                          I am on a project that is having the same problems- very slow pans- look fine in AE but when rendered stutter intermittent. I have tried everything- worked professionally in AE for 8 years first time I've ever encountered this. Looked and felt like a processor issue since the quicktime plays the stutter frames in different locations and they show up on different players. Project is due tomorrow I've tried everything- thinking I might have to try recreating it in finalcut.
                          • 10. Re: "Stuttering" when panning/zooming a still image...?
                            theboyk Level 1
                            Larry let me know if you try FCP. I did some testing out of FCP and had no issues like I was having out of AE. I just found the type was a little nicer out of AE but, next time, I might have to take a hit on the type quality if it means I get smoother playback?
                            k.
                            • 11. Re: "Stuttering" when panning/zooming a still image...?
                              Jonas Hummelstrand Level 2
                              You must approach this problem with a bit of logic:

                              1. If you get stutter at different times, the problem is not in AE or in the rendering, but rather in the playback. Kristin, you write that you get stutters while playing "1280 x 720 burned DVDs" which indicate that you are not burning a "Video DVD" (playable in a regular DVD player) but rather are playing data video clips from a data DVD (which is a much slower medium than a hard drive, which would explain why the video stutters: your computer can't read the data file fast enough.) Like I wrote earlier:
                              i "While playing in QuickTime Player, hit Cmd-I and see what it says under "Playing FPS." If it is less than what you rendered, your machine can't read/decode the video fast enough to play in realtime. "

                              2. If you always get stutters at exactly the same place each time you view it, it's probably because the movement between each frame is too large to fool your eyes/brain that it's a continuous motion. To fool your brain you need to make sure that there is less change between each frame, which can be done with one or several of the following suggestions:
                              A. Increase your frame rate.
                              B. If you are delivering for TV/DVD playback, render with fields to get twice the framerate (but half the vertical resolution.)
                              C. Turn on motion blur for all layers that are animated by AE and turn up the Shutter Angle in the Comp settings to get a stronger blur effect.
                              D. Animate the objects so they move slower.

                              I have yet to see an AE bug that would cause an otherwise smooth animation to jump, so I'm strongly suggesting you look at the other two reasons.

                              - Jonas Hummelstrand
                              http://generalspecialist.com/
                              • 12. Re: "Stuttering" when panning/zooming a still image...?
                                theboyk Level 1
                                Thanks Jonas,

                                1. The original comp is 1280 x 720 (as there was originally a need for it to be HD, but the plug got pulled on that after we'd started). So, when I render out, I'm rendering out at that size, but then DVD Studio Pro converts to 720 x 480i for a SD DVD. When viewing the SD DVD on an SD DVD player/widescreen TV (non-HD), I get no issue with an stutter. But, when I play back via the internal DVD player on a Mac, the stutter returns.

                                Also, when I render out of AE to an H.264 video file (full frame rate @ 29.97 FPS, full quality, size = half original) and play back on the Mac Pro (or any other of the 25+ Macs here) I get the stutter. When I view this video file in Quicktime Pro and watch the FPS, it's playing back at 29.97 FPS - 30 FPS, but not lower.

                                I can watch the animation frame-by-frame in AE and there is no stutter. When I view the same clip frame-by-frame in Quicktime (via the rendered H.264 files), I can see the jump that is 'causing the stutter effect.

                                Playing back to a TV is OK for now since it's working on the system we're presenting on, but I've yet been able to render a good quality video file for playback on a computer.

                                Again, I've also tested recreating the exact same sequence in FCP and had no issues with final renders (playing back DVD nor video file on desktop).

                                Regards,
                                Kristin.
                                • 13. Re: "Stuttering" when panning/zooming a still image...?
                                  Jonas Hummelstrand Level 2
                                  Sounds like issue 2, the movement between each frame is too large to fool your eyes/brain that it's a continuous motion. If you've rendered with fields, the DVD/TV can show each field (called "interlaced" rather than "progressive" display which is what computers use) and therefore give you twice the frame rate.

                                  There's normally a setting in computer-DVD-software that will let an interlaced source show as a progressive video by "de-interlacing" and showing both fields, effectively showing the same thing as on a TV. In Apple's DVD Player app, that option is found under "View -> Deinterlace."

                                  If you want it to look good playing from QuickTime you need to follow the earlier advices (A-D) plus NOT render with fields.

                                  - Jonas Hummelstrand
                                  http://generalspecialist.com/
                                  • 14. Re: "Stuttering" when panning/zooming a still image...?
                                    Great to see I'm not the only one struggling with this one.

                                    As mentioned above, when you view a DVD on your computer you are viewing at 29.97 progressive frames per second. The desktop display is not interlaced... so it combines the 2 interlace fields in each frame on the DVD into 1 progressive frame, effectively halving your temporal resolution (frame rate) and causing strobing or jerky motion.

                                    Your original footage is probably interlaced? which will give you nice smooth motion... but if you half that framerate (by going from interlace to progressive) ... you get the stutters.

                                    Answer: Shoot the engineers that came up with interlace, and also the guys that let it get into the HD spec. Everyone start using 1080p60 for everything so we can work towards a future where you can render one type of video that looks good on all common platforms.

                                    But seriously, getting video to look good just playing on your desktop monitor is REALLY hard... and involves limiting the types of fast camera motion as mentioned by previous posters.

                                    This is also why Pro's use files encoded with the correct codec played out a video playback card linked to a monitor that displays at the correct frame rate, which doesn't drop frames every time someone on the network checks there email or just munge or repeat frames to match the output display frequency.

                                    Real Answer: Try using something like a Canipus or DAC-200 firewire video interface (I'm sure people here can offer up the names of better cards that will give you HD playback via HDMI like black magic etc) and encoding your output files in the correct codec for that card or interface. This will allow you to playback smooth interlaced video from your computer onto an interlaced TV or monitor.

                                    The other option is to take advantage of the fact your desktop can display 60 true frames progressive and render in that format which will give you the nice motion of interlaced video, with out destroying that clean lettering, but I cant say I've had much success with getting this to work so far :) Has anyone else?
                                    • 15. Re: "Stuttering" when panning/zooming a still image...?
                                      matt peberdy Level 1

                                      Hi Kristin

                                       

                                      Wondering if you ever got to the bottom of this stuttering issue. I have what is probably the same issue and wondered if you found a way round.

                                       

                                      Cheers

                                       

                                      Matt

                                      • 16. Re: "Stuttering" when panning/zooming a still image...?
                                        Rick Gerard Adobe Community Professional & MVP

                                        There are certain speeds that sync up with frame rates so that they cause judders, jitters, stuttering or whatever you want to call it. The slower the frame rate the more obvious the problem.

                                         

                                        If you've ever watched a western on TV or at the movies you've seen the stagecoach wheels turn backwards at various speeds. This is an example of the problem. It's actually called a stroboscopic effect. Mechanics, in the good old days when cars had carburetors and distributors, used to hook up a timing light to the #1 spark plug so that a light flashed on a timing mark on the crankshaft pulley. This light had the effect of stopping the rotation visually. That's exactly what's happening when you are moving your photograph across the frame at one of the critical speeds. Your eye is fooled and your brain can't process the movement smoothly.

                                         

                                        There are also other cases where the sub pixel interpolation between frames causes areas of detail to flicker between frames. The latter problem can be seen by viewing your comp a frame at a time while zoomed in to say 800% and observing the edge detail. This problem can be especially nasty when you're trying to do a smooth title or credit roll. The horizontal lines that make up fine type can almost completely vanish between fields or frames if the text is moving at the wrong speed. You can test this out by creating a single pixel high horizontal line in AE and animating it from bottom to top of the frame. The only speed where you'll get a nice solid line in every frame or field is one that is an exact multiple of the frame rate. IOW, 1 frame 1 pixel of movement, 1 frame 2 pixels of movement, and so on. Move at 1 frame and 1.33 pixels of movement and the line will appear to completely disappear then return.

                                         

                                        If you are working at 24fps progressive you'll find that the juddering caused by motion at critical speeds is much more problematic than projects at 29.97 fps. Interlacing, as was mentioned before, helps and gives you a wider range of motion, but interlacing can introduce more pronounced flickering in the detail if you are right at one of these critical speeds.

                                         

                                        This problem extends to shooting as well. Cinematography manuals contain critical panning speed charts that list the number of degrees per second you can pan with various lens (angle of view) and shutter speed combinations. There isn't a videographer out there that's tried shooting 24P video and not ended up with an unusable pan due to these critical speeds.

                                         

                                        The solution to successfully animating detailed images is to use the right speed (pixels per second) for your frame rate, add extra motion blur to hide the problem, or reduce the amount of detail in the image. These are the only solutions that I know of. They all limit design and timing, but what good is your design if it makes your eyes go buggy.

                                         

                                        The best way I know if to tell if the problem is a playback issue is to use a device or program that tells you when you're dropping frames. You can use QT (by looking at the playback rate) or in FC or PPro by having the program report dropped frames. If it's a data rate issue you need more horsepower or a better codec. 

                                        • 17. Re: "Stuttering" when panning/zooming a still image...?
                                          Mylenium Most Valuable Participant

                                          Your answer is tops, Rick! Todd should save it and add it to a separate section in the help...

                                           

                                          Mylenium

                                          • 18. Re: "Stuttering" when panning/zooming a still image...?
                                            matt peberdy Level 1

                                            Hi Rick

                                             

                                            Thanks for your very detailed reply.

                                             

                                            Matt

                                            • 19. Re: "Stuttering" when panning/zooming a still image...?
                                              Todd_Kopriva Level 8
                                              > Your answer is tops, Rick! Todd should save it and add it to a separate section in the help...

                                               

                                              If Rick (or anyone) wants to submit material for such use in Help, I'm very happy to receive and use it. Even more immediately, someone could add this question and answer to the FAQ list for this forum.

                                              • 20. Re: "Stuttering" when panning/zooming a still image...?
                                                vidkidfx

                                                I'm also having this issue but what I don't understand is that if it's an illusion issue with the speed of the animated object then why do all the people having this issue report that RAM previews play perfectly at the projects full frame rate with no stuttering illusion?